Fuel-barrier polyamide resin and multilayer shaped article

Abstract

The fuel-barrier polyamide resin of the present invention is a product of the polycondensation of a diamine component comprising 70 mol % or higher of m-xylylenediamine and a dicarboxylic acid component comprising 70 mol % or higher of a mixed dicarboxylic acid which comprises a C 4 to C 20 α,ω-linear aliphatic dicarboxylic acid and at least one dicarboxylic acid selected from the group consisting of isophthalic acid and naphthalenedicarboxylic acid in a molar ratio of 30:70 to 95:5. The polyamide resin is excellent in not only fuel-barrier property and heat resistance, but also moldability and recyclability, and therefore suitably used as a barrier material of fuel containers.

1. A fuel-barrier multilayer molded article comprising a laminated structure of a layer made of a polyamide resin and a high-density polyethylene, wherein the polyamide resin is a polyamide resin produced by the polycondensation of a diamine component comprising 70 mol % or higher of m-xylylenediamine and a dicarboxylic acid component comprising 70 mol % or higher of a mixed dicarboxylic acid which comprises a C 4  to C 20  α,ω-linear aliphatic dicarboxylic acid and at least one dicarboxylic acid selected from the group consisting of isophthalic acid and naphthalenedicarboxylic acid in a molar ratio of 30:70 to 95:5. 
     
     
       2. The fuel-barrier multilayer molded article according to  claim 1 , wherein the polyamide resin contains smectite treated with an organic swelling agent in an amount of 1 to 20% by weight based on a total weight of the polyamide resin and the smectite. 
     
     
       3. The fuel-barrier multilayer molded article according to  claim 1 , wherein the mixed dicarboxylic acid is a mixture of the C 4  to C 20  α,ω-linear aliphatic dicarboxylic acid and isophthalic acid in a molar ratio of 3:7 to 9:1. 
     
     
       4. The fuel-barrier multilayer molded article according to  claim 3 , wherein the polyamide resin has a melting point of 160 to 220° C. 
     
     
       5. The fuel-barrier multilayer molded article according to  claim 3 , wherein the polyamide resin has a melt viscosity of 1000 to 5000 Pa·s when measured at a molding temperature and a shear rate of 100 sec −1 . 
     
     
       6. The fuel-barrier multilayer molded article according to  claim 1 , wherein the mixed dicarboxylic acid is a mixture of the C 4  to C 20  α,ω-linear aliphatic dicarboxylic acid and naphthalenedicarboxylic acid. 
     
     
       7. The fuel-barrier multilayer molded article according to  claim 6 , wherein the polyamide resin has a melting point of 160 to 225° C. 
     
     
       8. The fuel-barrier multilayer molded article according to  claim 6 , wherein the polyamide resin has a melt viscosity of 200 to 5000 Pa·s when measured at a molding temperature and a shear rate of 100 sec −1 . 
     
     
       9. The fuel-barrier multilayer molded article according to  claim 1 , wherein said laminated structure has a layer made of said polyamide resin and a layer of the high-density polyethylene. 
     
     
       10. The fuel-barrier multilayer molded article according to  claim 9 , wherein an adhesive resin layer is provided between each pair layers of the layer made of said polyamide resin and said layer of the high-density polyethylene. 
     
     
       11. The fuel-barrier multilayer molded article according to  claim 9 , wherein the layer made of said polyamide resin has a thickness of 0.001 to 1 mm, and the layer of the high-density polyethylene has a thickness of 0.01 to 20 mm. 
     
     
       12. The fuel-barrier multilayer molded article according to  claim 1 , which comprises a blend of the polyamide resin and high-density polyethylene in said layer. 
     
     
       13. The fuel-barrier multilayer molded article according to  claim 6 , wherein said mixed dicarboxylic acid includes the C 4  to C 20  α,ω-linear aliphatic dicarboxylic acid and the naphthalenedicarboxylic acid in a molar ratio of 40:60 to 90:10. 
     
     
       14. The fuel-barrier multilayer molded article according to  claim 1 , wherein the high-density polyethylene is ultrahigh-molecular high-density polyethylene. 
     
     
       15. The fuel-barrier multilayer molded article according to  claim 9 , wherein the high-density polyethylene is ultrahigh-molecular high-density polyethylene. 
     
     
       16. The fuel-barrier multilayer molded article according to  claim 1 , wherein said layer is capable of being a barrier material for fuel containers. 
     
     
       17. The fuel-barrier multilayer molded article according to  claim 9 , wherein said layer made of said polyamide resin is capable of being a barrier material for fuel containers.